[PATCH v4 14/16] iommu/arm-smmu: Unregister IOMMU and bus ops on device removal

[Will Deacon]

When removing the SMMU driver, we need to clear any state that we
registered during probe. This includes our bus ops, sysfs entries and
the IOMMU device registered for early firmware probing of masters.

Signed-off-by: Will Deacon <will@xxxxxxxxxx>
---
 drivers/iommu/arm-smmu.c | 50 ++++++++++++++++++++++++++++++++--------
 1 file changed, 40 insertions(+), 10 deletions(-)

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 5d2f60bb9e50..1f0c09bf112a 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -2009,25 +2009,51 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev,
 	return 0;
 }
 
-static void arm_smmu_bus_init(void)
+static int arm_smmu_bus_init(struct iommu_ops *ops)
 {
+	int err;
+
 	/* Oh, for a proper bus abstraction */
-	if (!iommu_present(&platform_bus_type))
-		bus_set_iommu(&platform_bus_type, &arm_smmu_ops);
+	if (!iommu_present(&platform_bus_type)) {
+		err = bus_set_iommu(&platform_bus_type, ops);
+		if (err)
+			return err;
+	}
 #ifdef CONFIG_ARM_AMBA
-	if (!iommu_present(&amba_bustype))
-		bus_set_iommu(&amba_bustype, &arm_smmu_ops);
+	if (!iommu_present(&amba_bustype)) {
+		err = bus_set_iommu(&amba_bustype, ops);
+		if (err)
+			goto err_reset_platform_ops;
+	}
 #endif
 #ifdef CONFIG_PCI
 	if (!iommu_present(&pci_bus_type)) {
 		pci_request_acs();
-		bus_set_iommu(&pci_bus_type, &arm_smmu_ops);
+		err = bus_set_iommu(&pci_bus_type, ops);
+		if (err)
+			goto err_reset_amba_ops;
 	}
 #endif
 #ifdef CONFIG_FSL_MC_BUS
-	if (!iommu_present(&fsl_mc_bus_type))
-		bus_set_iommu(&fsl_mc_bus_type, &arm_smmu_ops);
+	if (!iommu_present(&fsl_mc_bus_type)) {
+		err = bus_set_iommu(&fsl_mc_bus_type, ops);
+		if (err)
+			goto err_reset_pci_ops;
+	}
+#endif
+	return 0;
+
+err_reset_pci_ops: __maybe_unused;
+#ifdef CONFIG_PCI
+	bus_set_iommu(&pci_bus_type, NULL);
 #endif
+err_reset_amba_ops: __maybe_unused;
+#ifdef CONFIG_ARM_AMBA
+	bus_set_iommu(&amba_bustype, NULL);
+#endif
+err_reset_platform_ops: __maybe_unused;
+	bus_set_iommu(&platform_bus_type, NULL);
+	return err;
 }
 
 static int arm_smmu_device_probe(struct platform_device *pdev)
@@ -2173,7 +2199,7 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
 	 * ready to handle default domain setup as soon as any SMMU exists.
 	 */
 	if (!using_legacy_binding)
-		arm_smmu_bus_init();
+		return arm_smmu_bus_init(&arm_smmu_ops);
 
 	return 0;
 }
@@ -2187,7 +2213,7 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
 static int arm_smmu_legacy_bus_init(void)
 {
 	if (using_legacy_binding)
-		arm_smmu_bus_init();
+		return arm_smmu_bus_init(&arm_smmu_ops);
 	return 0;
 }
 device_initcall_sync(arm_smmu_legacy_bus_init);
@@ -2202,6 +2228,10 @@ static int arm_smmu_device_remove(struct platform_device *pdev)
 	if (!bitmap_empty(smmu->context_map, ARM_SMMU_MAX_CBS))
 		dev_err(&pdev->dev, "removing device with active domains!\n");
 
+	arm_smmu_bus_init(NULL);
+	iommu_device_unregister(&smmu->iommu);
+	iommu_device_sysfs_remove(&smmu->iommu);
+
 	arm_smmu_rpm_get(smmu);
 	/* Turn the thing off */
 	arm_smmu_gr0_write(smmu, ARM_SMMU_GR0_sCR0, sCR0_CLIENTPD);
-- 
2.24.1.735.g03f4e72817-goog